Cherenkov ring fit
- GlueX commissioning data
- geometrical reconstruction
- bar #3, central region (phi =~-90)
- pions with [3.8,4.2] GeV/c momentum
- without per-pixel corrections
- without lut corrections
Cherenkov photon in the coordinate system of the detector:
![](/~rdzhigad/data/gluex/ring/gluex_lut.png)
Cherenkov photon in the coordinate system of the charge particle:
![](/~rdzhigad/data/gluex/ring/gluex_ring.png)
Geant4 (bar + optical box ambiguities):
Geant4 with correct path in optical box (only bar ambiguities are left):
Commissioning data (pions only):
Event by event fit (mix of pions and kaons). Green line shows expected Cherenkov angle assuming ideal tracking (center of the ring in (0,0)); red - fitted:
Cherenkov ring fit of the accumulated sample of pions without correction (15 mrad cut around expected value):
![](/~rdzhigad/data/gluex/ring/hRing_ncorr.png)
![](/~rdzhigad/data/gluex/ring/hAngle_ncorr.png)
Cherenkov ring fit of the accumulated sample of pions after correction (equivalent to correction of the bar rotation):
![](/~rdzhigad/data/gluex/ring/hRing_acorr.png)
![](/~rdzhigad/data/gluex/ring/hAngle_acorr.png)
=> improved SPR
Cherenkov ring fit after event by event correction:
![](/~rdzhigad/data/gluex/ring/hRing_ecorr.png)
![](/~rdzhigad/data/gluex/ring/hAngle_ecorr.png)
=> further improved SPR